A disk apparatus for reading and writing high-density data on a disk is known. The disk apparatus reads and writes data by moving a pickup head while the disk loaded on a turntable is spinned.
The turntable is supported on a lifting frame that moves up and down in a body chassis of the disk apparatus. The pickup head is supported by a guide shaft fixed to the lifting frame, and moves along the guide shaft in a radial direction of the disk. The lifting frame is in a down position when a disk is unloaded. After a disk is inserted, the lifting frame moves up and the disk is loaded onto a chucking head of the turntable. Thereby, the disk apparatus is ready to read or write data on the disk.
Slimming down of such disk apparatus has been promoted. However, if the disk apparatus is made excessively slim, the guide shaft may interfere with a bottom plate of a body chassis when the lifting frame is moved up and down. To slim down the disk apparatus and prevent interference between the guide shaft and the bottom plate, it is necessary to reduce the diameter of the guide shaft. However, the diameter of the guide shaft is formed in accordance with a shape of a shaft receiving section provided in the pickup head. When the diameter of the guide shaft is only reduced, the pickup head may become unsteady. On the other hand, changing the shape of the pickup head to cope with the slimming down of the disk apparatus requires a custom-ordered pickup head and causes significant cost increase.
To solve the above problems, in Japanese Patent Laid-Open Publication No. 2004-334943, a leaf spring is attached to a pickup head. A guide shaft inserted through a shaft receiving section is pressed against the shaft receiving section with the leaf spring. Thereby, the pickup head is kept steady even if it is a conventional pickup head and the guide shaft has a smaller diameter than the shaft receiving section.
In the above publication, the leaf spring needs to be fixed to the pickup head with screws or adhesives, requiring time and effort to assemble the disk apparatus. As a result, assemblability of the disk apparatus decreases and assembly costs increase. In addition, since the guide shaft is pressed only with the leaf spring, unsteadiness (shake) of the pickup head is not surely prevented when the diameter of the guide shaft is excessively smaller than the shape of the shaft receiving section. Such unsteadiness causes fluctuations in the optical axis of laser beams from the pickup head, resulting in reading and writing errors. Recently, a technology to draw patterns and letters on a disk surface with laser beams from the pickup head has been developed, and it requires high precision mechanisms in the disk apparatus so as to perform drawing with high resolution.
To prevent unsteadiness of the pickup head, a collar may be provided between the guide shaft and the guide shaft receiving section to fill a gap therebetween. However, high processing precision is necessary in producing the collars capable of surely preventing the unsteadiness, resulting in increase in production costs.